Wobbler actuating piston for barrel engines



May 9, 1939. H. ALFARO 2,157,586

WOBBLER ACTUATING PISTON FOR BARREL ENGINES Originall Filed Oct. 16, 1955 2 Sheets-Sheet l u nl.

INVENTOR HeracZ/io lfaro A TORNEYS v`1:19.4- BY May 9, 1939. H, ALFARO 2,157,586

WOBBLER ACTUATING PISTON FOR BARREL ENGINES Original Filed Oct. 16, 1935 2 Sheets-Sheet 2 INVENTOR TTORNEYS Patented May 9, 1939 UNITED STATES PATENT OFFICE ENG INES

Heraclio Alfaro, Boston, Mass. Original application October 16, 1935, Serial No.

45,290. Divided and this application July 30,

1937, Serial No. 156,429

1 Claim.

'I'he present invention relates to engines of the wobbler cam or barrel type, particularly engines of the two-stroke cycle type having two pistons per cylinder, the improvements being in the cam actuating pistons of such engines and parts associated with the pistons.

This application is a division of my application Serial No'. 45,290, led October 16, 1935.

The present invention has for an object to provide a piston which has eiective means for applying thrust to the wobbler cam and for receiving the thrust of the cam.

A further object is to provide a piston provided with means for rigidly supporting cam engaging thrust rollers and so constucted as to readily permit mounting or removal of the rollers.

With the above and other objects in View the invention may be said to comprise the piston as illustrated in the accompanying drawings hereinafter described and particularly set forth in the appended claim together with such variations and modifications thereof as will be apparent to one skilled in the art to which the invention appertains.

Reference should be had to the accompanying drawings forming a part of this specification, in which:

Figure l is a longitudinal section through one of the pistons showing portions of the associated cylinder, wobbler cam and engine shaft;

Fig. 2 is a top plan View oi the outer end of the piston shown in Fig. 1;

Fig. 3 is an end elevation end of the piston;

35 Fig. 4 is a sectional view showing a piston of slightly modified construction;

Fig. 5 is an end elevation of the piston shown in Fig. 4;

Fig. 6 is a sectional view showing a piston embodying the invention in which the skirt is oi composite sheet metal construction;

Fig. '7 is a section taken on the line indicated at 1-1 in Fig. 6;

Fig. 8 is a section taken at 8-8 in Fig. 6;

Fig. 9 shows the oil scaping ring in elevation;

Fig. l is a plan view of the oil scoop bracket viewed as indicated at Ill-II) in Fig. 3; rn In the accompanying drawings there is shown one of the cylinders I of a barrel engine which is disposed parallel to the cental engine shaft 2 to which is attached a wobbler cam 3 through which the linear movements of the pistons impart rotary motion to the shaft. One of the pistons 4 is looking at the outer on the line indicated shown, it being understood that all of the pistons of the engine are alike.

The piston 4 has a tubular skirt 5 which may be formed integrally with the head of the piston. The skirt 5 is preferably stiened by regularly spaced longitudinally extending internal ribs 6. Two diametrically opposite ribs 6 terminate at their outer ends in bearing bosses I and 8, one on the side of the skirt adjacent the shaft 2 and the other in the outer side of the skirt. A bore is cut through the skirt 5 and boss 'i at an oblique angle to the piston axis and an alined bore is cut into the inner boss 8 to a depth sufficient to form a socket for a tubular shaft 9 which seats at its opposite ends in the bosses l and The shaft 9 provides a bearing for a beveled thrust roller I) which rolls upon the inner face of the cam 3.

The outer portion of the skirt 5 has an in* tegral extension I I which at its outer end has integral laterally extending arms I2 terminating in bearings I3 adapted to slide on fixed guide rods I4, the arms I2 providing a cross head on the piston between the guide rods. At its outer end between the inner ends of the arms I2, the extension l I has a thickened central portion I5 pron vided with an oblique opening to receive a bolt I which secures in place a short shaft Il which provides a supporting bearing for a beveled follower roller I8 which rolls upon the rear face of the wobbler cam 3 and serves to prevent excessive axial play between the piston and cam.

'Ihe outer end of the inner side of the skirt 5 is separated from the body of the skirt in a plane across the center of the boss 'I as indicated at I9 in Fig. 1 to form a detachable member 2 which is secured to the body of the skirt by bolts ZI screwed into apertures in the halves of the boss l.

To mount the bevel roller III within the skirt 5 the detachable member 2) is removed, the roller II) is slipped into place between the bosses 'i and 8 and the shaft 9 is inserted through the roller into the socket in the boss 8 after which the portion is bolted in place. The shaft 9 is held against turning movements by a dowel 22. A thrust washer 23 interposed between the roller I and the boss 8 and a dowel 24 holds the thrust washer against turning movements.

The cam 3 has the peripheral roller engaging portion 25 thereof oiset inwardly with respect to the body of the cam to provide an annular end portion which is adapted to enter the slots the outer ends of the pistons. The offset portion provides an internal substantially cylindrical shoulder 26 which closely overlies an oil collecting scoop 21 formed at the end of the detachable member 2!! of the skirt. A nozzle 28 discharges oil against the inner face of the cam and this oil is thrown out by centrifugal force along the face of the cam, maintaining a lm of oil on the internal shoulder 26. An annular baifle plate 29 may be attached to the cam to prevent any oil being thrown away from the face of the cam. The baffle plate 29 flares inwardly from the face of the cam and has an outer marginal portion which is positioned close to the face of the cam so that any oil moving outwardly either on the surface of the cam or the inner face of the baffle plate is directed in. a thin lm outwardly to the internal shoulder 25.

A passage 3l is formed in the detachable mei ber il of the skirt and extends from the oil collecting scoop to the opening in the boss 'l registering with an aperture 32 in the shaft 9 to deliver oil to the interior of the shaft. The opening through the boss 'l is closed by the inner end portion 33 of the detachable member 2! to prevent leakage of oil and the hollow shaft 9 has an opening 34 midway between its ends on the side opposite that against which the thrust of the roller is exerted. The opening 34 delivers oil to the bearing of the roller lil on the side where there is the least pressure so that there is an ampie supply of oil to the roller bearing. Near its outer end the shaft :'i has an opening 35 which permits flow of oil from the interior of the shaft 9 to a passage St extending through the extension il to the roller supporting portion i5. The bolt i5 is provided with an axial passage 3? which delivers oil from the passage 35 into the interior of the shaft l 'l which has a lateral opening 38 to the roller bearing. Lateral passages 39 in the arms i2 deliver oil from the passage 36 to the cross head bearings i3.

During operation of the engine, oil is automatically delivered from the cam face to the bearings of the thrust and follower rollers and to the crosshead bearings.

In engines of the two-stroke cycle type having opposed pistons in each cylinder and ports opening through the cylinder wall, it is difficult to avoid leakage of oil into the ports and to the combustion chamber due to the scraping of oil off the piston skirt into the ports during movements of the piston past the ports.

At the open end of the cylinder l there is mounted an oil scraping ring 4i? which engages the piston skirt 5 which sweeps the oil from the exterior surface of the skirt during the inward stroke of the piston, thereby saving oil which would otherwise be scraped off into ports in the s' cylinder wall and leak into the scape ahead of the piston and be consumed with the fuel.

The oil scraping ring iii is a resilient split ring which may be constructed like an ordinary piston ring mounted in a retaining ring 46d detachably secured to the end of the cylinder and is backed by a spring 4535 interposed between the exterior periphery of the ring 4i? and the bottom of the channel formed between the ring 4ta and the edge of the cylinder, the spring lib "j" serving to maintain a suitable pressure between a continuous the interior of the ring 46 and the surface of the piston skirt. The portion of the skirt 5 with which the scraper ring engages preferably has smooth cylindrical surface without recesses in which oil can accumulate so that the skirt can be swept clean by the scraper ring. The exterior surface of the closure forming portion 33 of the member 2ii`is machined to conform to the exterior surface of the skirt so that there is no recess for accumulation of oil at the opening through which the roller shaft 9 is inserted.

In Figs. 4 and 5 of the drawings there is shown a slightly modified construction in which the piston skirt 5a is provided with internal bosses il and it at the inner and outer sides thereof to support a tubular obliquely disposed shaft 43 which provides a bearing for the thrust roller 44. In this instance the skirt is bored through the outer boss 42 providing an aperture 45 through which the shaft 43 may be inserted and a socket in the boss 4 to receive the inner end of the shaft 43. At its outer end the shaft 43 is closed by a head 45 and the shaft is secured in place by means of a bolt 4l' which extends through the skirt wail at the inner end of the shaft and through the head 4S. A dowel 48 is provided to hold the shaft 43 against rotation. A crosshead extension 4G is detachably secured to the body of the skirt outwardly of the boss 42 by means of bolts rIhe thrust roller 44 is inserted into the outer end of the skirt 5a before the extension 45 is attached and after the roller 44 is positioned between the bosses 4I and 42 the shaft is inserted and secured in place.

The wobbler cam 3a has its marginal thrust roller engaging portion inwardly offset and within the shoulder of the cam there is provided an oil groove 5i into which oil is directed by the inner of the cam and the baiile 29a.

An oil scoop in the form of a tubular member is secured to the end of the skirt body outw diy of the boss 4i by bolts which are screwed in the apertures 53 shown in Fig. 5. The scoop has a laterally bent outer end portion 54 posiin the oil groove 5l of the cam. A passage 55 in the skirt leads from the oil scoop to socket in boss 4l and the shaft 43 has an erture 55 registering with the passage 55. Midway between its ends the tubular shaft 43 has i opening 5i through which lubricant is supplied to the roller bearing. At its outer end the shaft 43 has an aperture 58 opening to a passage 59 in the skirt which leads to a passage 60 in the cross head extension 49 from which oil is supplied to the bearing of the follower roller and to the cross head bearings.

In Fig. S of the drawings there is shown a piston having a head 6l which may be formed of an aluminum alloy or other suitable metal having high heat conductivity and a thin metal skirt 52 formed of sheet steel or steel tubing and secured to the head 5l by suitable means such as bolts 53. Supporting bosses 55 and 64 for opposite ends of a thrust roller be secured by welding or brazing to the interior of the sln'rt 52, the skirt 52 being provided with an opening registering with the inner socket E54v to permit the roller supporting shaft tov be insei-ted. In order to permit the thrust roller to be inserted into the skirt a scoop extension 5'! is provided which is detachable, the inner end of the extension closing the open end of 'the socket B4 and being detachably secured to the socket by bolts as in the modification shown in Fig. 1. The skirt 5f! is reenforced interiorly by longitudinal bracing elements @i3 which are formed of sheet metal and V-shaped to form internal ribs when secured to the interior of the skirt 52 by welding or brazing. Two of the bracing elements 7 53 are in alinement with the bosses 64 and 65 and are welded or braced to the bosses. bracing members are of a sleeve t5 'Ihe skirt 52 The preferably an integral part which ts within the piston skirt.

supporting shaft may and sleeve are provided'with ing;

tegral portions extending outwardly of the boss 65 which are welded or brazed together to form a hollow extension 10 and hollow arms H extending laterally from the extension l0. A sleeve 12 for supporting the follower roller is welded or brazed to the outer end of the hollow extension 'Ill and bearing sleeves 13 are welded or brazed to the outer ends of the arms 1I.

Lubrication of the roller and cross head bearings is substantially the same as described in detail in connection with Fig. l.

An aperture 14 is provided in the boss 65 through which oil may flow from the interior of the roller supporting shaft into the hollow extension 10. An aperture 15 in the sleeve 12 permits low of oil to the bearing of the follower roller. The hollow arms 1I communicate with the hollow extension 'I0 and apertures '16 are provided in the crosshead bearing sleeves 13 to lubricate the same.

It will be apparent that the present invention provides a piston having a rigidly attached crosshead and interiorly mounted cam engaging rollers which possesses the necessary rigidity and which can readily be assembled in operative relation to the cam and which can be readily disassembled to permit repair or replacement of parts.

It will further be apparent that simple and effective means are provided for automatically lubricating roller and crosshead bearings during operation of the engine, and for preventing excessive loss of oil through the cylinder ports or by leakage into the combustion chamber.

Furthermore, it is to be understood that the particular form of apparatus shown and described, and the particular procedure set forth, are presented for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as described in the appended claim.

What I claim is:

A piston for barrel engines having a skirt provided at the open end thereof with a crosshead extension at one side thereof which has spaced guide engaging bearings, a roller mounted upon the interior of the skirt, a second roller mounted on said extension intermediate said crosshead bearings, an extension on the side of the skirt diametrically opposite the crosshead extension, one of said extensions being detachably connected to the skirt to permit mounting of the roller upon the interior of the skirt.

HERACLIO ALFARO. 

